摘要
研究表明在铝合金中加入Ti、Zr、B等元素,并合理分配它们的比例份额可以提高铝合金的耐热性,同时保持较好的导电性及强度。但对结果的理论解释研究较少。
通过扫描电镜测试及透射电镜测试研究了在纯铝中添加Ti、Zr、B等元素后的生成物及其对铝合金微观组织的影响,实验表明在原子数目比为(Ti+Zr)：B>1：2的3种不同样品中不仅有六方结构的TiB2、ZrB2存在,还有立方结构的Al3Ti和Al3Zr存在；而在原子数目比为(Ti+Zr)：B=1：2的3种不同样品中只发现了六方结构的TiB2、ZrB2晶粒。另外金相结果显示原子数目比为(Ti+Zr)：B>1：2的3种样品的晶粒度普遍小于原子数目比为(Ti+Zr)：B=1：2的3种样品。即当原子数目比为(Ti+Zr)：B=1：2时,细化程度不明显,对电子的散射较少,导电性能受影响较少。
通过EET理论中的键距差法(Bond Length Difference,简称BLD方法)分别计算了TiB2、ZrB2、Al3Ti和Al3Zr的键能、共价电子数。结果表明TiB2的最强键键能、最强键的共价电子数远大于Al3Ti的最强键键能、最强键的共价电子数,所以Ti元素优先和B元素结合成TiB2,当B元素消耗完,Ti元素再与Al结合成Al3Ti。ZrB2的最强键键能、最强键的共价电子数远大于Al3Zr的最强键键能、最强键的共价电子数,所以Zr元素优先和B元素结合成ZrB2,当B元素消耗完,Zr再与Al结合成Al3Zr。即六方结构的TiB2、ZrB2优先于立方结构的Al3Ti和Al3Zr生成。这就解释了扫描电镜的实验结果：当原子数目比为(Ti+Zr)：B=1：2时,只发现了六方结构的晶粒(TiB2、ZrB2)；当原子数目比为(Ti+Zr)：B>1：2时,既有六方结构的晶粒(TiB2、ZrB2)存在,又有立方晶格结构的晶粒(Al3Ti、Al3Zr)存在。
分别计算α-Al与TiB2、ZrB2、Al3Ti和Al3Zr的最相似面的电子面密度差。Al3Ti的(111)面和α-Al的最相似面(111)面的电子面密度差1.11%远小于TiB2的(0001)面与α-Al的最相似面(110)面的电子面密度差40.88%；Al3Zr的(111)面和α-Al的最相似面(111)面的电子面密度差20.05%远小于ZrB2的(0001)面与α-Al的最相似面(110)面的电子面密度差87.09%。因为电子面密度差越小,两种物质电子的连续性越好,越有助于α-Al的异质形核,细化效果越显著。所以原子数目比为(Ti+Zr)：B>1：2的样品的晶粒度普遍小于原子数目比为(Ti+Zr)：B=1：2的样品的晶粒度,与金相实验的结果相符合。而晶粒越小,晶界对电子的散射就越严重,进而降低合金的导电性。所以,控制Ti、Zr、B的添加量,使原子数目比为(Ti+Zr)：B=1：2,此时只有TiB2、ZrB2生成,铝合金的导电性较好。
分别计算a-Al、TiB2、ZrB2、Al3Ti和Al3Zr的派-纳力,计算结果为：0.05002、14.03272、7.20934、0.43760、0.21664。TiB2、ZrB2、Al3Ti和Al3Zr派-纳力较大,位错无法从TiB2、ZrB2基体切过,只能采取绕过机制。当它们大量细小弥散地分布在铝基体中时,会对位错起到很好的钉扎效果,提高再结晶温度,使铝合金保持良好耐热性。
综合分析添加不同含量Ti、Zr、B后,对铝合金的导电性、耐热性的影响,可知应使Ti、Zr、B的原子数目比为(Ti+Zr)：B=1：2,此时铝合金既保持了良好的耐热性,又未降低导电性。
Research shows that adding Ti, Zr and B in the aluminum alloy, and rational allocation of their proportional share can improve the heat resistance of aluminum alloy, while maintaining good electrical conductivity and strength. But the theory research is less.
The product and the effect on the microstructure of aluminium alloy of adding Ti, Zr and B in pure aluminium are researched by scanning electron microscopy and Transmission electron microscope. Experiments show that there are hexagon TiB2, ZrB2and cubic Al3Ti, Al3Zr in the presence of3different samples of the atomic number ratio (Ti+Zr):B>1:2; while only hexagon TiB2, ZrB2is found in3different samples of atomic number ratio (Ti+Zr):B=1:2. In addition the metallographic results show that grain size of3samples of atomic number ratio (Ti+Zr):B>1:2is generally less than that of3samples of the atomic number ratio (Ti+Zr):B=1:2. When the atomic number ratio (Ti+Zr):B=1:2, refining effect is not obvious, electron scattering is less, the conductive property is less influenced.
By the bond length difference method (referred to as BLD) of EET, the bond energy and covalent electron number of TiB2, ZrB2, Al3Ti and Al3Zr were calculated. The results show that the energy of the strongest bond of TiB2, the covalent electron number of the strongest bond is far greater than the energy of the strongest bond of Al3Ti, the covalent electron number of the strongest bond, so TiB2has priority, when B is consumed, Ti and Al bind to Al3Ti The energy of the strongest bond of ZrB2, the covalent electron number of the strongest bond is far greater than the energy of the strongest bond of Al3Zr, the covalent electron number of the strongest bond, so ZrB2has priority, when B is consumed, Zr and Al are combined into Al3Zr. Hexagon lattice structure of TiB2, ZrB2prior to the cubic lattice structure of Al3Ti and Al3Zr. This explains the results of scanning electron microscope:when the atomic number ratio (Ti+Zr):B=1:2, only hexagon lattice existence (TiB2, ZrB2) is found; when the atomic number ratio (Ti+Zr):B>1:2, there are six square lattice (TiB2, ZrB2) and cubic lattice (Al3Ti, Al3Zr).
Surface electron density differences of α-Al with TiB2, ZrB2, Al3Ti an Al3Zr were calculated. Surface electron density difference (1.11%) of Al3Ti (111) and α-Al (111) is far less than that(40.88%) of TiB2(0001) and α-Al (110); Surface electron density difference (20.05%) of Al3Zr (111) and α-Al (111) is far less than that (87.09%) of ZrB2(0001) and α-Al (110). The lower the surface electron density is, the better the coherent relationship between the two substances, the more heterogeneous nucleation in α-Al, the better the effect of refinement. So the grain size of the atomic number ratio (Ti+Zr):B>1:2is generally less than that of the atomic number ratio (Ti+Zr):B=1:2. This is consistent with the result of metallographic experiment. And the smaller the grain, the electron scattering from grain boundary is more serious, and the conductivity of the alloy is reduced. Therefore the electrical conductivity of aluminum alloy is better when the atomic number ratio is (Ti+Zr):B=1:2and only TiB2and ZrB2generate.
The Peierls-Nabarro forces of α-Al, TiB2, ZrB2, Al3Ti and Al3Zr were calculated. The results are as follows:0.05002,14.03272,7.20934,0.43760,0.61224. The Peierls-Nabarro forces of TiB2, ZrB2, Al3Ti and Al3Zr are so large that dislocations can not cut them and can only take the bypass mechanism. When a large of fine TiB2, ZrB2, Al3Ti and Al3Zr disperse in the aluminum matrix, dislocation will be pinned well and recrystallization temperature will be improved and aluminum alloy will have good heat resistance.
After analyzing the influence of conductivity and heat-resistance of aluminum alloy of adding different content Ti, Zr and B, we should make the atom ratio of Ti, Zr and B (Ti+Zr):B=1:2. Then the aluminum alloy can keep good heat-resistance and does not reduce the conductivity.
引文
[1]贾祥磊,朱秀荣,陈大辉等.耐热铝合金研究进展[J].兵器材料科学与工程,2010,33(2)：108-112
[2]卢凯明,申作家.耐热导线的发展和现状分析[J].电气时空,2003,(8)：18-19
[3]孙德勤,潘琰峰,高健等.高强耐热全铝合金导线的研究与开发[J].轻合金加工技术,2006,34(8)：5-8
[4]Setzer W C,Boone G W.The Use of Aluminium/boron Master Alloys to Improve Electrical Conductivity[J].Light Metal,1992:337-343
[5]彭宁云,黎继军.新型耐热铝合金导线输电技术的应用研究[J].广东电力,2010,23(2)：18-22
[6]O.A.Romanova. Heat-resistant Wrought Aluminum Alloys and Prospects of Their Development [J].Metal Science and Heat Treatment,1983,25(7):479-484
[7]A.S.Shigarev,S.V.Nosenko,A.M.Katok et al. Phase and Chemical Composition of the Aluminum Coating on Heat Resistant Alloys[J].Metal Science and Heat Treatment,1971,13(8):655-658
[8]孙海安,杨金魁,李晖.均匀化制度对导线用耐热铝合金电导率的影响[J].轻金属,2002,(9)：58-61
[9]郑云鹏.合金元素对铝锆耐热合金杆性能影响规律的实验研究[D].硕士学位论文.沈阳：东北大学,2006
[10]尤传永.耐热铝合金导线的耐热机理及其在输电线路中的应用[J].电力建设,2003,24(8)：4-8
[11]A.I.Rybnikov,L.B.Getsov,A.A.Tchizhik et al. Service Life of Heat-resistant Alloys with Protective Coatings in Thermocyclic Loading[J].Surface and Coatings Technology,1996,78(1):103-112
[12]万建成,朱宽军,刘胜春等.国产耐热导线的机电性能研究[J].电力建设,2008,29(12)：37-40
[13]孔繁玉.国外铝芯电线电缆概况[J].电线电缆,1974,(4)：80-83
[14]杜晓东.架空铝导线性能提高途径及机理研究[J].电线电缆,1998,(6)：2-6
[15]Wang Jianhua, Yi Danqing, Wang Bin. Microstructure and Properties of 2618-Ti Heat Resistant Aluminum Alloy [J]. Transaction of Nonferrous Metals Society of China,2003,13(3):590-594
[16]宋谋胜,刘忠侠,李继文等.加钛方式与钛含量对A356合金组织和性能的影响[J].中国有色金属学报,2004,14(10)：1729-1735
[17]Mukhopadhyay A K, Shiflet GJ. Role of vacancies on the precipitation processes in Zr modified aluminum based alloys [J]. Scripta Metall et Materialia,1989,24(2):307-312
[18]谢优华,杨守杰,戴圣龙等.锆元素在铝合金中的应用[J].航空材料学报,2002,22(4)：56-61
[19]杜晓东,刘永忻,李合琴.微量锆对导电铝合金耐热性的影响[J].热加工工艺,1995,(2)：20-21
[20]SPITTLEJA, SADLIS. The influence of zirconium and chromium on the grain refining efficiency of Al-Ti-B inoculants[J]. Cast Metals,1994,7(4):247-253
[21]Xie Youhua, Yang Shoujie, Dai Shenglong et al. Influences of element zirconium on cast microstructure and granularity of ultra-high strength aluminum alloy [J].The Chinese Journal of Nonferrous Metals,2002,12(S1):131-135
[22]王桂芹,李丰庆,李长茂等.硼对含硅铝和含铁铝导电性能的影响[J].特种铸造及有色合金,2003,(3)：15-17
[23]张红耀,陈敬超,杨钢等.硼对工业纯铝显微组织的影响[J].有色金属,2006,(2)：41-44
[24]单鹏,杨异,刘凤芹.B对含Zr铝合金微观组织的影响机理[J].特种铸造及有色合金,2009,29(10)：964-966
[25]L. LU, M. O. LAI, H. Y. WANG. Synthesis of titanium diboride TiB2 and Ti-Al-B metal matrix composites [J]. Journal of materials science,2000, (35):241-248
[26]J.L.Murray, P.K. Liao and K.E.Spear. The B-Ti (Boron-Titanium) system [J]. Bulletin of Alloy Phase Diagrams,1986,7(6):550-555
[27]H.Okamoto.B-Ti (Boron-Titanium) [J].Journal of Phase Equilibria and Diffusion,2006, 27(3):303
[28]胥锴,刘政,刘萍.稀土在铝及铝合金中的应用现状与展望[J].有色金属加工,200534(5)：10-14
[29]刘顺华,王桂芹,高洪吾等.稀土元素对铝导体的导电性的影响[J].机械工程材料,2005,29(10)46-49
[30]Hirschbom I S.Recent applications of the rare earth metals on nonferrous metallurgy[J]. Metals,1970,22 (10):40-43
[31]潘复生,丁培道,周守则.稀土在我国铝合金中的应用现状与动向[J].材料导报,1989,(6)：15-19
[32]李文,关振中.固体与分子经验电子理论及其应用和发展[J].金属材料研究,1997,23(1)：13-17
[33]孙振国.相平面价电子结构及其在合金研究中的应用[D].博士学位论文.南京：南京理工大学,2007
[34]吴畏,张瑞林.键距差方法中等同键数值的计算机计算方法[J].吉林大学自然科学学报,1993,(4)：57-60
[35]余瑞璜.古体与分子经验电子理论[J].科学通报,1978,(2)：217-224
[36]于鹏恩.合金平面价电子结构与合金马氏体中合金元素原子杂化状态的确定[D].硕士学位论文.镇江：江苏科技大学,2008
[37]付宝勤.基于固体与分子经验电子理论的表面能分析及计算[D].硕士学位论文.北京：北京化工大学,2010
[38]李志林,刘志林,孙振国.合金相结构因子和界面结合因子的计算方法及其在合金设计中的应用[J].金属学报,1999,35(7)：673-681
[39]刘伟东.合金价电子结构计算及其应用[D].上海：上海交通大学,2005
[40]屈华,刘伟东,张坤等.Ti3Al基合金(0001)α2//(110)β界面价电子结构分析[J].稀有金属材料与工程,2005,34(10)：1569-1573
[41]Bruce L. Bramfitt.The effect of carbide and nitride additions on the heterogeneous nucleation behavior of liquid iron[J]. Metallurgical and Meterials Transactions,1970,1(7): 1987-1995
[42]刘志林.界面电子结构与界面性能IM].北京：科学出版社,2002
[43]Chen Jinju, Feng Zhesheng, Jiang Meilian et al. The effect of anodizing voltage on the electrical properties of Al-Ti composite oxide film on aluminum[J].Journal of Electroanalytical Chemistry,2006,(2):26-31
[44]Ye Yicong, He Liangju, Li Peijie. Differences of grain-refining effect of Sc and Ti additions in aluminum by empirical electron theory analysis [J].Transactions of Nonferrous Metals Society of China,2010,(20):465-470
[45]李培杰,叶益聪,何良菊.Sc和Ti对纯铝细化机理的价电子结构分析[J].科学通报,2008, 53(11)：1345-1349
[46]张坤,刘伟东,屈华等.α2-Ti3Al的价电子结构及合金化[J].辽宁工学院学报,2004,24(5)：36-39
[47]惠林海,耿浩然,王守仁等.Al3Ti金属间化合物的研究进展[J].机械工程材料,2007,31(9)：1-4
[48]李文,张瑞林,余瑞璜.Ti-Al系金属间化合物的价电子结构分析[J].物理化学学报,1999,15(9)：824-829
[49]李文,关振中,王沛枝.Ti-Al系金属间化合物的价电子结构与其力学性能的关系[J].机械工程材料,1996,20(2)：9-12
[50]张东升,王杰芳,苟微娟.Ti对纯Al晶粒细化作用的电子理论分析[J].特种铸造及有色合金,2011,31(7)：664-667
[51]马洪涛,李建国,张柏清.Al-Ti-B合金的组织分析[J].中国有色金属学报,2001,11(5)：801-805
[52]王宝龙,赵俊国,王文武.TiB2材料的特性及其在铝工业中的应用[J].轻金属,2004,(5)：23-26
[53]章桥新.TiB2的价电子结构及其性能研究[J].陶瓷学报,2000,21(3)：159-161
[54]苏文勇,张瑞林.TiB2等C32型化合物价电子结构分析[J].北京理工大学学报,2000,20(5)：550-554
[55]纪嘉明,周飞,李忠华.TiB2和ZrB2晶体结构与性能的电子理论研究[J].中国有色金属学报,2000,10(3)：358-360
[56]贾堤,董治中,于申军.TiMe合金的价电子结构分析及结合能计算[J].稀有金属材料与工程,1998,27(3)：152-155
[57]J.Murraay, A.Peruzzi and J.P.Abriata. The Al-Zr (Aluminum-Zirconium) System [J].Journal of Phase Equilibria,1992,13(3):277-289
[58]韩杰才,李金平,孟松鹤等.(ZrTi)B2固溶体的价电子结构与性能[J].稀有金属材料与工程,2007,36(2)：12-15
[59]J.S.Peters, B.A.Cook, J.L.Harringa. Erosion resistance of TiB2-ZrB2 composites[J]. Wear, 2009,267:136-143
[60]章照,赵玉涛,程晓农等.A1-Zr-B体系反应合成复合材料的组织和性能[J].特种铸造及有色合金,2006,26(8)：512-514
[61]Li Jinping, Dong Shanliang, Meng Songhe et al.Calculation of crystal cohesive energy of ZrB 2 compound [J].Front. Mater. Sci. China,2010,4(3):245-250
[62]Li Jinping, Wang Yan, Liu Qing etal.Effect of the La addition content on valence electron structure and properties of ZrB2 ceramics [J].Front. Mater. Sci. China,2010,4(3): 262-265
[63]章桥新.锆的难熔化合物价电子结构[J].中国有色金属学报,2000,10(4)：516-518
[64]赵品,谢辅洲,孙振国.材料科学与基础教程[M].哈尔滨：哈尔滨工业大学出版社,2009
[65]李承荃.Bravais晶格点阵广义晶面(HKL)及面间距dHKL取值探讨[J].安徽工学院学报,1992,11(3)：83-93
[66]宫秀敏,朱勇,周一志.关于FCC和BCC点阵晶面间距计算式的证明[J].武汉工学院学报,1991,13(1)：51-57
[67]范建春,李丽琳,陈超球.晶面间距dhkl的两种求法[J].广西师院学报,1999,16(1)：92-97
[68]杨通,梁艳峰,董晟全,(TiB2+Al3Ti)/Al-4.5Cu原位复合材料的相结构与力学性能[J].铸造技术,2005,26(10)：887-891
[69]李高宏,李建平,夏峰等.Al3Ti-TiB2-SiC/Al-13Si复合材料的增强机理[J].西安工业学院学报,2005,25(5)：449-454
[70]王娜,唐壁玉.L12型铝合金的结构、弹性和电子性质的第一性原理研究[J].物理学报,2009,58：230-233
[71]姚强,邢辉,孟丽君等.TiB2和TiB弹性性质的理论计算[J].中国有色金属学报,2007,17(8)：1297-1301
[72]江东亮,张景贤,林庆玲等.水基流延成型制备ZrB2和ZrB2-20vol% SiC复合材料的微观结构和抗热震性能[J].无机材料学报,2011,26(3)：244-248